(2) Field of the Invention
The present invention relates to a data input-output device for a camera, and more particularly to a data input-output device for a camera that outputs data converted from input data generated by opening and closing two switches as a plurality of digital data by random logic.
(2) Description of the Related Art and Problems To Be Solved By the Invention
As disclosed in Japanese Utility Model Application Laid-Open No. 1-149624 entitled "Controller for Camera", both the input and output terminals of prior art data input-output devices for cameras are comprised of one terminal, respectively, and the binary states of each input and output terminal are controlled by a central processing unit (CPU).
In Japanese Patent Application No. 1-201613 entitled "Encoder Device", data taken out of mechanical elements decoded according to function is decoded as digital data by an A/D converting circuit built in a CPU.
The device described in the aforementioned Japanese Utility Model Application Laid-Open No. 1-149624 has the drawbacks that it only reduces the number of input ports for the CPU and that it cannot determine the state when both of two switches are closed.
The device described in Japanese Patent Application No. 1-201613 has the drawbacks that it requires an A/D converter of either the counter type or the double integral type, both of whose circuits are so complex that they cannot be used for fast data input/output of a camera and the like and which have a limited range of use.